title: A randomized trial of the effect of automated ventricular capture on device longevity and threshold measurement in pacemaker patients.
abstract: BACKGROUND
  An automatic capture (AC) algorithm adjusts ventricular pacing output to capture the ventricle while optimizing output to 0.5 V above threshold. AC maintains this output and confirms capture on a beat-to-beat basis in bipolar and unipolar pacing and sensing.
  
  
  OBJECTIVE
  To assess the AC algorithm and its impact on device longevity.
  
  
  METHODS
  Patients implanted with a pacemaker were randomized 1:1 to have the AC feature on or off for 12 months. Two threshold tests were conducted at each visit- automatic threshold and manual threshold. Average ventricular voltage output and projected device longevity were compared between AC on and off using nonparametric tests.
  
  
  RESULTS
  Nine hundred ten patients were enrolled and underwent device implantation. Average ventricular voltage output was 1.6 V for the AC on arm (n = 444) and 3.1 V for the AC off arm (n = 446) (P < 0.001). Projected device longevity was 10.3 years for AC on and 8.9 years for AC off (P < 0.0001), or a 16% increase in longevity for AC on. The proportion of patients in whom there was a difference between automatic threshold and manual threshold of <or=0.5 V through follow-up was 99.0% (95% CI: 98.6, 99.3). The average difference between automatic threshold and manual threshold was 0.07 V (P = 0.002).
  
  
  CONCLUSIONS
  This study showed that automatic threshold testing at follow-up provided comparable information to manually measured threshold testing. AC provided a significant increase in projected device longevity compared to standard programing.
authors.affiliation: Brigham and Women's Hospital, Boston, Massachusetts 02115, USA. bkoplan@partners.org
authors.forename: Bruce A
authors.initials: BA
authors.lastname: Koplan
authors.forename: David M
authors.initials: DM
authors.lastname: Gilligan
authors.forename: Luc S
authors.initials: LS
authors.lastname: Nguyen
authors.forename: Theodore K
authors.initials: TK
authors.lastname: Lau
authors.forename: Lisa M
authors.initials: LM
authors.lastname: Thackeray
authors.forename: Kellie Chase
authors.initials: KC
authors.lastname: Berg
mesh_terms: D000368:Aged; D000465:Algorithms; D004562:Electrocardiography / Q000706:statistics & numerical data*; D004868:Equipment Failure / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013813:Therapy, Computer-Assisted / Q000379:methods* / Q000706:statistics & numerical data*; D016896:Treatment Outcome; D014481:United States / Q000453:epidemiology; D014693:Ventricular Fibrillation / Q000453:epidemiology* / Q000517:prevention & control*